Current antimicrobial treatment recommendations for melioidosis, the disease caused by Burkholderia pseudomallei, are largely based on studies of strains isolated from the Eastern Hemisphere (EH), where most human cases are identified and reported. In this study, we evaluated the antimicrobial susceptibility of 26 strains in the CDC (Centers for Diseases Control and Prevention) collection from the Western Hemisphere (WH) isolated from 1960 to 2015. Minimal inhibitory concentration (MIC) values were measured by standard broth microdilution for 16 antimicrobials following Clinical and Laboratory Standards Institute (CLSI) guidelines. Twenty-four of the 26 WH strains were susceptible to the six antimicrobials with CLSI-defined MIC susceptibility interpretive criteria for B. pseudomallei: amoxicillin/clavulanate, ceftazidime, imipenem, doxycycline, tetracycline, and trimethoprim/sulfamethoxazole. One WH strain demonstrated intermediate amoxicillin/clavulanate resistance and another strain had intermediate resistance to tetracycline. For all antimicrobials tested, the susceptibility profiles of WH isolates were comparable with previously reported MIC results of EH strains. The overall similarities suggest that the same antimicrobials are useful for melioidosis treatment in both the WH and EH. Using in silico analyses of WH genomes, we identified a novel amino acid substitution P258S in the beta-lactamase PenA, which may contribute to decreased susceptibility to amoxicillin/clavulanate in B. pseudomallei.

中文翻译：

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鼻疽伯克霍尔德氏菌西半球分离株的抗菌敏感性：表型和基因组分析


目前针对类鼻疽（由类鼻疽伯克霍尔德氏菌引起的疾病）的抗菌治疗建议主要基于对东半球（EH）分离菌株的研究，大多数人类病例都是在东半球发现和报告的。在这项研究中，我们评估了 CDC（疾病控制与预防中心）从 1960 年至 2015 年从西半球 (WH) 收集的 26 株菌株的抗菌敏感性。最小抑菌浓度 (MIC) 值通过标准肉汤微量稀释法测量遵循临床和实验室标准协会 (CLSI) 指南的 16 种抗菌药物。 26 种 WH 菌株中有 24 种对符合 CLSI 定义的鼻疽伯克氏菌MIC 敏感性解释标准的六种抗菌药物敏感：阿莫西林/克拉维酸、头孢他啶、亚胺培南、多西环素、四环素和甲氧苄啶/磺胺甲恶唑。一种 WH 菌株表现出中度阿莫西林/克拉维酸耐药性，另一种菌株对四环素具有中度耐药性。对于所有测试的抗菌药物，WH 分离株的敏感性特征与之前报道的 EH 菌株的 MIC 结果相当。总体相似性表明，相同的抗菌药物可用于 WH 和 EH 的类鼻疽治疗。通过对 WH 基因组的计算机分析，我们在 β-内酰胺酶 PenA 中发现了一个新的氨基酸取代 P258S，这可能有助于降低类鼻疽杆菌对阿莫西林/克拉维酸的敏感性。